Armillaria mushrooms

What Is Armillaria & How Does It Affect Trees?

Armillaria (or honey fungus) is a parasitic fungi that lives on trees and woody shrubs and includes 10 species formerly lumped together as A. mellea. Armillaria can be extremely destructive to trees and shrubs, but it is often under-diagnosed because it is difficult to properly identify. However, it is one of the most common diseases of landscape plants.

The Armillaria fungus works as both a pathogen and a saprophyte (breaks down dead wood), making it deadly to your trees. The most obvious way to spot Armillaria Root Disease is when its mushrooms pop up around the base of your tree.

**It is important to note that there are a ton of different mushrooms that can pop up around your tree’s roots that can often be harmless. So, before assuming that any mushroom growth can be deadly to your tree, have a professional properly identify the species of mushroom.**

Here are a list of symptoms that may help in identifying a tree infection caused by the Armillaria fungus.   

  • Honey-colored or brown to yellowish mushrooms clumped together at the base of your tree.
    • These mushrooms don’t present often, and because of this, this infection can run its course in your tree without you ever spotting these mushrooms.
Armillaria mushrooms
Image from www.bartlet.com
  • Shoestring Mycelium (thick black string-like structures often spotted under the bark or near the roots in the soil)
    • This is often seen in heavily infected trees
Armillaria Shoestring Mycelium
Image from www.commons.wikimedia.org
  • Mycelial Fans
    • This is found below the bark
Armillaria Mycelial Fans
Image found on www.forestrydev.org
  • Discharge from the main stem
    • This can often be a sign of other issues your tree may be suffering from, but this may lead you to shoestring Mycelium and Mycelial fans likely meaning your tree is suffering from a Armillaria infection.
Armillaria oozing
Image found on www.bartlett.com

In many cases, there are methods to slow down the disease and ultimately extend your tree’s life. If properly diagnosed, a professional can help to put together a plan to best deal with the pathogen. While there are often ways to extend your trees life after it has been infected with the Armillaria fungus, the structural integrity of the tree may become compromised and this could lead to a safety hazard. If it is determined that your tree is not structurally sound enough, and it is marked a safety hazard to people or your home, it will likely need to be removed. If you suspect your tree may be suffering from any sort of disease or infection, please contact the professionals at Red Cedar to have your situation properly inspected and properly diagnosed. The first step to rehabilitation is a proper diagnosis so the best course of action can be put into place!

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